Increased knowledge of vascular function during chronic periodontal disease is likely to add to the knowledge of the disease process and of the prognosis for tissue recovery. The effect on bone metabolism of the vascular changes known to occur during chronic inflammation of the periodontium has not been investigated. The objective of this research is to determine the role of blood vessels in alveolar bone resorption in dogs. Using an implanted minipump, a localized area of bone will be exposed to continuous infusions of low concentrations of mediators of either vascularization or resorption. The vascular response associated with bone resorption will be measured as follows: vascular surface area and volume as determined by stereologic morphometry of l micron thick histologic sections; vessel type and numbers found as determined by stereologic morphometry and electron microscopy; sites of vessel growth as determined with autoradiography. Morphologic characteristics will be assessed using cleared, perfused tissue specimens.